1. Field of the Invention
The present invention relates to a liquid jet head unit and a liquid jet device, both of which include a liquid jet head for ejecting liquid to be jetted. More specifically, the present invention relates to an inkjet recording head unit and an inkjet recording device, both of which include an inkjet recording head. In the inkjet recording head, a part of a pressure generating chamber communicating with a nozzle orifice, through which ink droplets are ejected, is constituted of a vibration plate. A piezoelectric element is provided thereto by use of this vibration plate. Ink droplets are ejected depending on displacement of the piezoelectric element.
2. Description of the Prior Art
Inkjet recording devices such as inkjet printers and plotters include an inkjet recording head unit (hereinafter referred to as a “head unit”) provided with an inkjet recording head which can eject ink in the form of ink droplets, the ink reserved in an ink reserving portion such as an ink cartridge and an ink tank.
The unit head includes an inkjet recording head, a head case and a cover head. The inkjet recording head includes nozzle rows constituted of nozzle orifices which are arranged side by side in each of the nozzle rows. The head case is fixed to the inkjet recording head at the side of ink supply ports. The cover head protects a surface of the inkjet recording head, through which surface ink droplets are ejected (hereinafter, referred to as an “ink-droplet ejecting surface”). In this respect, a method of manufacturing a nozzle plate has been proposed. In the case of this method, a water repellent process is applied, by use of an electroless plating technique, to exposed parts in a nozzle plate constituting the inkjet recording head and an inner surface of each of the nozzle orifices. Thereby, coatings are formed on the exposed parts in the nozzle plate, and the inner surface of each of the nozzle orifices. (See Japanese Patent Laid-open Official Gazette No. Tokkai. Hei. 9-123461 (Scope of the claim, Page 3 and FIG. 1), for example)
However, if coatings (water repellent films) are provided to all of the exposed parts in the nozzle plate by means of applying the water repellent process to the exposed parts of the nozzle plate, this brings about a problem that the water repellent films make smaller adhesive strength with which the nozzle plate is adhered to another member in a case where the nozzle plate is fixed to the member with an adhesive agent interposed therebetween.
With this problem taken into consideration, another method of manufacturing a nozzle plate has been proposed. In the case of this method, the nozzle plate is provided with a water-repellent-processed surface which is obtained by applying a water repellent surface treatment, and a non-water repellent-processed surface in the periphery of the nozzle plate which is obtained by applying no water repellent surface treatment. This non-water repellent portion is adhered to, and joined to, a cover head with an adhesive agent interposed between the non-water repellent portion and the cover head. The cover head is shaped like a box, and covers the nozzle plate. (See Japanese Patent Laid-open Official Gazette No. Tokkai. Hei. 10-34920 (Page 3 and FIGS. 1 to 2), for example)
However, in a case where the water repellent film is formed on the nozzle plate as disclosed in Japanese Patent Laid-open Official Gazettes No. Tokkai. Hei. 9-123461 and No. Tokkai. Hei. 10-34920, this brings about a problem as follow. A ratio at which the minute nozzle orifices contrast with the areas provided with the water repellent films is low. This makes it difficult to identify the nozzle orifices. Accordingly, it is difficult to align the inkjet recording head with a holding member, such as a cartridge case to which an ink cartridge is attached, by use of the nozzle orifices.
In addition, there have existed head units, where nozzle rows in which nozzle orifices are arrange side by side are multiplied by use of a plurality of inkjet recording heads. Such head units require the nozzle rows of the neighboring inkjet recording heads to be relatively aligned with one another with high precision in order to improve printing quality. However, if the water repellent films are formed on the nozzle plate, this brings about a problem that the neighboring nozzle rows can not be relatively aligned with one another with high precision by use of the nozzle orifices. This is because it is difficult to identify the minute nozzle orifices.
It should be noted that such a problem exists not only in inkjet recording head units including inkjet recording heads for ejecting ink, but also in liquid jet head units including other liquid jet heads for ejecting liquid other than ink.